Make prepare script end on error

hack/prepare.sh

@@ -246,9 +246,10 @@ function get_ipv6() {
 	while read -r l1; do
 		if [ "$l1" != "::1/128" ]; then
 			echo ${l1%/*}
-			break
+			return
 		fi
 	done < <(ip -6 -o addr show lo | awk '{print $4}')
+	err "no ipv6 found"
 }
 
 function make_config() {
@@ -257,17 +258,27 @@ function make_config() {
 		return
 	fi
 
+	# To make error propagation work, need to assign separately
+	conf_pf0="$(get_ifname 0)"
+	conf_pf1="$(get_ifname 1)"
+	conf_vf_pattern="$(get_pattern ${devs[0]})"
+	conf_ipv6="$(get_ipv6)"
+	if [[ "$OPT_MULTIPORT" == "true" ]]; then
+		conf_pf1_proxy="$(get_pf1_proxy ${devs[1]})"
+		conf_pf1_proxy_vf="$(get_pf1_proxy_vf)"
+	fi
+
 	{ echo "# This has been generated by prepare.sh"
 	echo "no-stats"
-	echo "pf0 $(get_ifname 0)"
-	echo "pf1 $(get_ifname 1)"
-	echo "vf-pattern $(get_pattern ${devs[0]})"
-	echo "ipv6 $(get_ipv6)"
+	echo "pf0 $conf_pf0"
+	echo "pf1 $conf_pf1"
+	echo "vf-pattern $conf_vf_pattern"
+	echo "ipv6 $conf_ipv6"
 	if [[ "$OPT_MULTIPORT" == "true" ]]; then
 		echo "a-pf0 ${devs[0]},class=rxq_cqe_comp_en=0,rx_vec_en=1,dv_flow_en=2,dv_esw_en=1,fdb_def_rule_en=1,representor=pf[0-1]vf[0-$[$actualvfs-1]]"
 		if [[ "$OPT_PF1_PROXY" == "true" ]]; then
-			echo "pf1-proxy $(get_pf1_proxy ${devs[1]})"
-			echo "pf1-proxy-vf $(get_pf1_proxy_vf)"
+			echo "pf1-proxy $conf_pf1_proxy"
+			echo "pf1-proxy-vf $conf_pf1_proxy_vf"
 		fi
 		echo "multiport-eswitch"
 	else
@@ -278,7 +289,7 @@ function make_config() {
 	if [[ "$OPT_MULTIPORT" == "true" ]]; then
 		log "dpservice configured in multiport-eswitch mode"
 		if [[ "$OPT_PF1_PROXY" == "true" ]]; then
-			log "dpservice will create a PF1-proxy"
+			log "dpservice will create a pf1-proxy"
 		fi
 	else
 		log "dpservice configured in normal mode"